To handle each row element, apply templates in process-cols mode, which loops over all the col-spec elements and again USES dyn: evaluate to compute the text that is output for each column.

Dyn indicates whether the application environment is dynamic or static.

One interesting possibility might be to pass in an XPath to be used to test whether a template should be traced, and call the EXSLT Dynamic XPath Evaluation extension (dyn: evaluate ) to execute it.